I don't know what I would do without this lens. I literally wouldn't be able to take 2/3rds of the photos that I take without it. It is my work horse and it rarely leaves my camera. If you are thinking about buying it, do it. It's an amazing piece of glass. I would buy another one in a heartbeat if heaven forbid something happen to my original copy.
Thank you Sigma for leading the charge in camera innovation.